1. Field of the Invention
The invention relates to dynamic, controlled atmosphere exposure testing chambers useful for the testing of industrial hygiene monitors and for the development and verification of industrial hygiene air monitoring methods.
2. Description of the Prior Art
Controlled atmosphere exposure chambers have been widely used for the development and validation of industrial hygiene laboratory air sampling methods. Since dynamic systems are usually employed in generating the desired atmosphere, a number of variables are involved in controlling the system performance. These variables include the concentration of the contaminants (analytes), humidity, temperature, linear velocity, and atmospheric matrices (such as benzene in the presence of various concentrations of gasoline vapor). Previously reported testing chambers were usually designed for one type of testing requirement with the article under test at a single orientation. As a result, different chamber designs are used for different testing devices. This made it difficult to perform a method comparison for different types of industrial hygiene monitors.
The article by Dixon, S. W.; Vasta, J. F.; Freeland, L. T.; Calvo, D. J.; and Hemingway, R. E., entitled "A Multiconcentration Controlled Test Atmosphere System for Calibration Studies" (Am. Ind. Hyg. J. 45(2), 99-104, 1984) reported a design of a controlled atmosphere test system. The design used a vacuum manifold with a Teflon tube chamber for testing active air monitors. It also used a separate, custom made linear exposure chamber constructed with Teflon-filled glass for testing passive dosimeters.
Irikura, A. K., in a report entitled "The Dynamic Generation and Collection of Test Atmospheres" (Technical Progress Report WRC 218-82, Shell Development Company, Houston, Tex.) reported a glass manifold test chamber with thirty pieces of 1/4" o.d. Teflon tubing for testing the active charcoal monitors.
Joki, H. M., in a report entitled "Passive Dosimeters. I. An Evaluation of the 3M Brand Organic Vapor Monitor for Benzene Exposures" (Technical Progress Report WRC 113-80, Shell Development Company, Houston, Tex.) reported the use of a stainless steel manifold with six single dosimeter exposure chambers for testing passive dosimeters.
Anderson, C. C., et al, in an article entitled "Generation of Test Atmospheres of Toxic Substances for Air Sampling Methods Evaluation" (175th ACS National Meeting, Mar. 15, 1978) reported a cone-shaped exposure chamber with tube fittings for testing active sampling devices.
Freeland, L. T., in an article entitled "An Industrial Hygiene Calibration Manifold", Am. Ind. Hyg. Assoc. J. 38(12) 712-720, 1977 reported a jacketed glass sampling manifold for testing tube type industrial hygiene monitors.
Perkin-Elmer Model ATD 50 Thermal Desorption Application Note No. 14, entitled "The Generation of Reference Atmospheres for the Calculation of Diffusive Uptake Rates." (TDA-14, Perkin-Elmer) reported the design of an exposure chamber for testing tube-type diffusive passive dosimeters.